<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        .a{color: #ff0000}
        .b{color: lime}
        #aaa{color: aqua ; background-color: #f56600}
    </style>
</head>
<body>
<div class="a">div1</div>
<div class="b">div2</div>
<div id="aaa">div3</div>
<div>div4</div>
<div>div5</div>
<div>div6</div>
</body>
</html>